On April 4, 1949, the United States and eleven other countries met in Washington, DC, to sign the North Atlantic Treaty. The signing was part of a historic shift in U.S. foreign policy after World War II: rather than go it alone in peacetime as it had for the previous 150 years, the United States would stand with others. The North Atlantic Treaty Organization (NATO) thereby became America’s first peacetime alliance outside the Western Hemisphere. Today, twenty-nine countries make up what is the greatest military alliance in history, one that continues to serve U.S. interests.